International Women’s Day highlights the unique contributions women have made and continue making to our society. However, economically speaking, women are both powerful and underrepresented.

In the United States, women now comprise six in 10 of today’s college graduates. They also account for nearly half the workforce and hold more than half of the country's personal wealth. Women also influence 70% to 80%of all purchasing decisions worldwide. Yet, despite this substantial impact, women hold only about one in five board seats at both Fortune 500 and Fortune 1000 companies.

The need for more women on boards extends beyond simply having a more proportionate share of seats at the table. Today’s companies face extraordinary competition in an economy that puts an unprecedented premium on knowledge. To maintain or gain an edge over their competitors, companies must harness all available talent, and that means fully leveraging the best and brightest women in today’s talent pool.

And that should be a priority in the boardroom.

Indeed, there’s a correlation between companies with gender-diverse boards and those that enjoy greater returns on equity, sales, and invested capital, according to research from McKinsey & Company.

Putting more women on boards also makes for good corporate governance.

A high-performing board consists of a group that generates and carries out the best ideas. Those ideas arise only when a diverse pool of thought is brought to the table. With a gender imbalance, boards can experience “group think” and fail to see and account for perspectives that could enhance company performance. In contrast, boards with gender diversity more closely reflect society and thus may have better insight into their multiple constituents, which include customers, employees, owners and operating communities.

In light of these benefits, how can companies increase female representation on their boards?

A simple yet effective approach calls for filling every other vacant seat with a woman. If companies adopted this “Every Other One” approach while retaining existing female seats, women would occupy about a third of board seats in five years – certainly a step in the right direction.

Gender parity would eventually follow.

Skeptics often argue that a supply problem stands in the way of adding substantially more women to corporate boards.

This argument is simply false. There are about 150 female Russell 3000 CEOs, 60 women CFOs in the S&P 500, 330 women CHROs in the S&P 500, 5,145 female law partners, and 165,000 female-owned firms with revenues greater than $1 million. If boards consider such talent, progress will be easy. But, if boards look only for female CEOs within the Fortune 500, then they have created a supply problem.

Companies can achieve greater female representation rather quickly if they expand the criteria for directors. Nominating committees, specifically, should consider appointing successful female divisional presidents, small- to medium-business owners, entrepreneurs, management consultants, non-profit executives, foundation heads, financial service executives and university presidents. This constitutes just a partial list of the sources of likely qualified candidates.

Women make up the majority of all of business’s constituencies, and yet they currently don’t have the chance to influence the decisions that impact them.

It’s been long contended that board diversity would increase as women comprised a growing portion of the workforce, yet progress has moved and still moves at a snail’s pace.

On International Women’s Day and through Women’s History Month, we should reflect on the many contributions made by women. As we do, let’s also remember the contributions they could make if we added them to corporate boards. “Every Other One,” it’s the least we can do.

Steve Odland is the CEO of the Committee for Economic Development and sits on the board of directors for General Mills, Inc. and Analogic Corporation. He also is the former CEO of Office Depot and AutoZone.

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